driver core: Redefine the meaning of fwnode_operations.add_links()

 * resource reservation conflict on the memory window that the efifb

 * framebuffer steals from the PCIe host bridge.

 */

static int efifb_add_links(const struct fwnode_handle *fwnode,

static int efifb_add_links(struct fwnode_handle *fwnode,

			   struct device *dev)

{

	struct device_node *sup_np;

 *			       endpoint node.

 * @graph_get_port_parent: Return the parent node of a port node.

 * @graph_parse_endpoint: Parse endpoint for port and endpoint id.

 * @add_links:	Called after the device corresponding to the fwnode is added

 *		using device_add(). The function is expected to create device

 *		links to all the suppliers of the device that are available at

 *		the time this function is called.  The function must NOT stop

 *		at the first failed device link if other unlinked supplier

 *		devices are present in the system.  This is necessary for the

 *		driver/bus sync_state() callbacks to work correctly.

 *

 *		For example, say Device-C depends on suppliers Device-S1 and

 *		Device-S2 and the dependency is listed in that order in the

 *		firmware.  Say, S1 gets populated from the firmware after

 *		late_initcall_sync().  Say S2 is populated and probed way

 *		before that in device_initcall(). When C is populated, if this

 *		add_links() function doesn't continue past a "failed linking to

 *		S1" and continue linking C to S2, then S2 will get a

 *		sync_state() callback before C is probed. This is because from

 *		the perspective of S2, C was never a consumer when its

 *		sync_state() evaluation is done. To avoid this, the add_links()

 *		function has to go through all available suppliers of the

 *		device (that corresponds to this fwnode) and link to them

 *		before returning.

 *

 *		If some suppliers are not yet available (indicated by an error

 *		return value), this function will be called again when other

 *		devices are added to allow creating device links to any newly

 *		available suppliers.

 *

 *		Return 0 if device links have been successfully created to all

 *		the known suppliers of this device or if the supplier

 *		information is not known.

 *

 *		Return -ENODEV if the suppliers needed for probing this device

 *		have not been registered yet (because device links can only be

 *		created to devices registered with the driver core).

 *

 *		Return -EAGAIN if some of the suppliers of this device have not

 *		been registered yet, but none of those suppliers are necessary

 *		for probing the device.

 * @add_links:	Create fwnode links to all the suppliers of the fwnode. Return

 *		zero on success, a negative error code otherwise.

 */

struct fwnode_operations {

	struct fwnode_handle *(*get)(struct fwnode_handle *fwnode);

	(*graph_get_port_parent)(struct fwnode_handle *fwnode);

	int (*graph_parse_endpoint)(const struct fwnode_handle *fwnode,

				    struct fwnode_endpoint *endpoint);

	int (*add_links)(const struct fwnode_handle *fwnode,

	int (*add_links)(struct fwnode_handle *fwnode,

			 struct device *dev);

};